1. Field of the Invention
The present invention relates to a conducting polymer composition and an organic optoelectronic device including the same. More particularly, the present invention relates to a conducting polymer composition which is manufactured using a self-doped conducting polymer in which a conducting polymer chain is grafted in a polyacid, and is uniformly dissolved in water or an organic solvent, thereby having a good coating property and being easily blended with other organic polymers, and in which conductivity and a work function can be easily controlled according to the content of an additionally added ionomer, and to an organic optoelectronic device having high efficiency and a long lifetime.
2. Description of the Related Art
Optoelectronic devices convert light energy into electric energy or electric energy into light energy, and examples thereof include organic light emitting devices, solar cells, transistors, and the like. At present, many studies regarding the formation of conducting polymer films on the electrodes are being conducted to improve device efficiency by efficiently transporting electronic charges, that is, holes and electrons generated from the electrodes of an optoelectronic device into the optoelectronic active layers.
In particular, an organic light emitting device is an active light-emitting device in which electrons and holes combine in a fluorescent or phosphorescent organic compound thin film (hereinafter referred to as an organic film) when current is supplied to the organic film, thereby emitting light. In order to improve the efficiency of the organic light emitting device and reduce a driving voltage, the organic light emitting device generally has a multi-layer structure including a hole injection layer, an emissive layer, and an electron injection layer, etc., instead of single-layer structure only using an emitting layer. The hole injection layer can be formed using a conducting polymer.
In particular, an aqueous PEDOT (poly(3,4-ethylene dioxythiophene))-PSS (poly(4-styrenesulfonate)) dispersion, which is commercially available as Baytron P series products from H. C. Starck, GmbH, Germany, is widely used in the manufacture of an organic light-emitting device to form a hole injection layer by spin coating it on an ITO (indium tin oxide) electrode. The PEDOT-PSS, a hole injection material, has the following structure:

As above, a conducting polymer composition of PEDOT/PSS in which a polyacid of PSS (poly(4-styrenesulfonate)) is doped in a conducting polymer of PEDOT (poly(3,4-ethylene dioxythiophene)) is polymerized as a PEDOS/PSS composition by dissolving EDOT monomer in an aqueous PSS solution. However, the polymerized PEDOT/PSS composition has a particle size of more than 50 nm and exists in a dispersed state on a surface of water, and thus differences in conductivity, hole injection capability in OLED and thin film uniformity are significant according to the particle size. Besides, the resultant dispersions with PEDOT/PSS change its characteristics in each batch, and as a result, this incurs differences in the OLED device's performance.
Also, it is not recommended to use PSS because PSS in a PEDOT/PSS composition absorbs moisture well when a removal of moisture is required. Further, PSS can be decomposed by reaction with electrons to release a by-product such as sulfate, which may be diffused to an adjacent organic film, for example, an emissive layer. This diffusion of the material derived from the hole injection layer to the emissive layer induces exciton quenching, thereby resulting in a reduction in the efficiency and lifetime of the organic light emitting device.
Thus, a demand for a novel conducting polymer composition is increasing to obtain satisfactory device efficiency and lifetime in an optoelectronic device such as an organic light emitting device.